feat(client): gasless transactions for POLY_PROXY (Magic Link proxy wallet)

[cesarenaldi]

Summary

• Extends prepareGaslessTransaction to support WalletType.POLY_PROXY alongside the existing Safe flow
• Adds a new SignGaslessHashRequest workflow step for raw-hash personal signing
• Updates all three wallet adapters (viem, ethers-v5, privy) to handle the new signing step
• Adds relayHub address to EnvironmentConfig (production: 0xD216153c06E857cD7f72665E0aF1d7D82172F494)
• Adds encodeProxyCall() in abis.ts to encode the proxy factory proxy(...) ABI call

Why the proxy flow is different from Safe

Safe uses EIP-712 typed-data over a SafeTx struct. Proxy uses the original GSN relay hub signing protocol:

keccak256("rlx:" ++ from ++ to ++ data ++ relayerFee ++ gasPrice ++ gasLimit ++ nonce ++ relayHub ++ relay)

…then personal-sign (EIP-191) over that 32-byte hash. The calldata targets the proxy factory (proxyFactory address), not the wallet, and the relayer request type is PROXY not SAFE.

The implementation was verified against:

• relayer-v2/packages/api/pkg/signatures/hash.go — hash construction
• relayer-v2/packages/api/pkg/signatures/verify.go — personal-sign semantics
• relayer-v2/packages/api/pkg/validate/validate.go — isValidProxySigParams requirements
• builder-relayer-client/src/builder/proxy.ts — client-side reference

Files changed

File	What
environments.ts	Add relayHub: EvmAddress to config type + production value
abis.ts	Add encodeProxyCall()
workflow.ts	Add SignGaslessHashRequest
viem.ts / ethers-v5.ts / privy.ts	Handle signGaslessHash in completeWith
account.ts	Export deriveProxyWalletAddress as @internal
actions/gasless.ts	Proxy branch in prepareGaslessTransaction; buildProxyTransactionHash
testing.ts	deriveProxyAddress test helper
gasless.test.ts / clients.test.ts	Proxy wallet classification + workflow shape tests

Invariants preserved

• Safe flow is unchanged
• prepareGaslessWallet remains Safe-only
• EOA accounts still rejected by the invariant guard
• Public API surface is minimal — no new exported action functions

Test plan

• pnpm lint — passes (biome, no fixes needed)
• pnpm typecheck — passes (zero tsc errors)
• gasless.test.ts proxy suite — verifies signGaslessHash shape and rejects EOA
• clients.test.ts proxy classification — verifies walletType === POLY_PROXY for a deterministic proxy wallet

Residual risks / follow-ups

• Gas limit is hardcoded to 10_000_000 (reference client fallback). Gas estimation would require an RPC provider in the workflow — deferred.
• gasPrice: '0' and relay: ZERO_ADDRESS are acceptable per backend validation but carry no real relay signal.

🤖 Generated with Claude Code

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Note

Medium Risk
Touches transaction signing and relayer submission logic (hash construction, signature payloads, and environment addresses), where small mismatches can break execution. Changes are scoped to gasless workflows and covered by updated tests.

Overview
Adds gasless transaction support for WalletType.POLY_PROXY alongside the existing Safe flow by building a relayer-compatible proxy transaction hash ("rlx:" preimage) and submitting RelayerTransactionType.PROXY executions targeting the proxy factory.

Refactors the gasless signing step so signGaslessMessage now carries a raw 32-byte hex digest (Safe EIP-712 digests are precomputed; proxy uses the new hash builder), updates viem/ethers-v5/privy adapters accordingly, and extends environment/config + ABI helpers (relayHub address and encodeProxyCall). Tests are updated/added to cover proxy wallet classification and the new workflow shape.

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